Troy Lee Designs A1 Drone Adult All-Mountain Bike Helmet with TLD Shield Logo (Gray/Red, Medium/Large) Reinforced polycarbonate shell in-molded with the EPS liner extends down the sides and back of the head for maximum protection and durability 8 pressurized intake passages draw in cool air for maximum ventilation 8 rear vacuum vortex outlets help exhaust and draw heat from head Triple position adjustable retention system allows customized fit for various eyewear, head shape and riding styles Single piece, ultra plush, removable and washable comfort liner made of anti-microbial moisture wicking material for a dry, comfortable feel